Can run in a shared hosting? XML errors.

I have FCKeditor running fine fine in my development machine. Also, a test site in a small VPS account run fine.
But the real site will run on a shared hosting and I'm getting the error: "XML request error: Internal Server Error (500)" when I press the "Browse Server" button.

The hosting already gave full permissions to ASPNET user to the "UserFiles" account, also to the "IUSER_<computer_name>" account. What else do I need ?

Please, if anybody has successfully install FCKEditor in a shared hosting, raise your hand
I want to know if at least, is possible, to continue fighting, I have already a week with this